Function TransposeMatrix

source/opt/const_folding_rules.cpp:365–402

Returns to the constant that results from tranposing |matrix|. The result will have type |result_type|, and |matrix| must exist in |context|. The result constant will also exist in |context|.

// will have type |result_type|, and |matrix| must exist in |context|. The
// result constant will also exist in |context|.
const analysis::Constant* TransposeMatrix(const analysis::Constant* matrix,
                                          analysis::Matrix* result_type,
                                          IRContext* context) {
  analysis::ConstantManager* const_mgr = context->get_constant_mgr();
  if (matrix->AsNullConstant() != nullptr) {
    return const_mgr->GetNullCompositeConstant(result_type);
  }

  const auto& columns = matrix->AsMatrixConstant()->GetComponents();
  uint32_t number_of_rows = columns[0]->type()->AsVector()->element_count();

  // Collect the ids of the elements in their new positions.
  std::vector<std::vector<uint32_t>> result_elements(number_of_rows);
  for (const analysis::Constant* column : columns) {
    if (column->AsNullConstant()) {
      column = const_mgr->GetNullCompositeConstant(column->type());
    }
    const auto& column_components = column->AsVectorConstant()->GetComponents();

    for (uint32_t row = 0; row < number_of_rows; ++row) {
      result_elements[row].push_back(
          const_mgr->GetDefiningInstruction(column_components[row])
              ->result_id());
    }
  }

  // Create the constant for each row in the result, and collect the ids.
  std::vector<uint32_t> result_columns(number_of_rows);
  for (uint32_t col = 0; col < number_of_rows; ++col) {
    auto* element = const_mgr->GetConstant(result_type->element_type(),
                                           result_elements[col]);
    result_columns[col] =
        const_mgr->GetDefiningInstruction(element)->result_id();
  }

  // Create the matrix constant from the row ids, and return it.
  return const_mgr->GetConstant(result_type, result_columns);
}

const analysis::Constant* FoldTranspose(
    IRContext* context, Instruction* inst,